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Discordant Distortion in Cubic GeMnTe2 and High Thermoelectric Properties of GeMnTe2-x%SbTe
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-01-17 , DOI: 10.1021/jacs.2c12877
Jinfeng Dong 1, 2 , Yilin Jiang 1 , Yandong Sun 3 , Jue Liu 4 , Jun Pei 1 , Wei Li 1 , Xian Yi Tan 2, 5 , Lei Hu 6 , Ning Jia 2 , Ben Xu 3 , Qian Li 1 , Jing-Feng Li 1 , Qingyu Yan 2, 5 , Mercouri G Kanatzidis 7
Affiliation  

GeMnTe2 adopts a cubic rock salt structure and is a promising mid-temperature thermoelectric material. The pair distribution function analysis of neutron total scattering data, however, indicates that GeMnTe2 is locally distorted from the ideal rock salt structure with Ge2+ cations being discordant and displaced ∼0.3 Å off the octahedron center. By alloying GeMnTe2 with SbTe, the carrier concentration can be tuned in GeMnTe2-x%SbTe (x = 15.1), leading to converged multiple broad valence bands and a high Seebeck coefficient of >200 μV K–1 from 300 to 823 K. The system exhibits a large density-of-state effective mass of >10 me and a high weighted mobility of 80 cm2 V–1 s–1, leading to a power factor of 15 μWcm–1 K–2 at 823 K. The composition GeMnTe2-15.1%SbTe exhibits very low lattice thermal conductivity of ∼0.5 Wm–1 K–1 at 823 K, attributed to the combination of off-centering cations in the rock salt structure, Ge/Mn positional disorder, dislocations, and abundant Ge-rich and Mn-rich nanoparticles. A ZT value of ∼1.5 can be achieved for GeMnTe2-15.1%SbTe with a ZTave of 0.96 in the temperature range of 400–823 K.

中文翻译:

立方 GeMnTe2 的不一致畸变与 GeMnTe2-x%SbTe 的高热电性能

GeMnTe 2采用立方岩盐结构,是一种很有前途的中温热电材料。然而,中子总散射数据的对分布函数分析表明,GeMnTe 2局部扭曲了理想的岩盐结构,其中 Ge 2+阳离子不一致并且偏离八面体中心约 0.3 Å。通过将 GeMnTe 2与 SbTe 合金化,可以在 GeMnTe 2 - x %SbTe ( x = 15.1) 中调整载流子浓度,从而导致会聚的多个宽价带和从 300 到 823 K的 >200 μV K –1的高塞贝克系数. 该系统表现出大于 10 的大态密度有效质量m e和 80 cm 2 V –1 s –1的高加权迁移率,导致在 823 K 时的功率因数为 15 μWcm –1 K –2。成分 GeMnTe 2 -15.1%SbTe 表现出非常低的晶格热导率~ 0.5 Wm –1 K –1在 823 K,归因于岩盐结构中的偏心阳离子、Ge/Mn 位置无序、位错以及丰富的富 Ge 和富 Mn 纳米粒子的组合。在 400–823 K 的温度范围内, GeMnTe 2 -15.1%SbTeZT值为~1.5,ZT平均值为 0.96。
更新日期:2023-01-17
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